Used plastics or plastic waste typically have high percentages of foreign materials, e.g., metal parts, paper residue, glass, secondary plastics, and the like. Usually, these foreign materials or impurities must be removed before the plastics are reused. This is realized in several ways such that the used plastics are first plasticized by heating and the plastic melts are then filtered. For this purpose, so-called melt filters are used, through which the metallic or non-metallic foreign materials or higher melting point plastics are separated. However, to enable continuous and uninterrupted filtering, the melt filter must be cleaned continuously.
From U.S. Pat. No. 4,470,904, a separating device according to the class is known, in which the contaminated plastic melts are pressed into the interior of a hollow, cylindrically-shaped filter body arranged in a housing. In the interior of the filter body, there is a rotationally driven stripper shaft, which is arranged coaxial to this filter body and which defines an inner annular space with the inner wall of the filter body and carries on its outer side several strippers at an angle to the axial direction and expanding into a spiral. The residue detained on the filter body on its inner side is transported to a material outlet opposite the inlet end of the inner annular space in the axial direction along the filter body by the strippers through the rotation of the stripper shaft. The strippers are elastically pressed from their inner side onto the inner surface of the filter body. However, in such elastic contact of the strippers, there is the problem that the strippers can be lifted from the surface of the filter body due to the pressure of the plastic melts and thereby lose their effectiveness. On the other hand, too high a contact pressure leads to increased friction between the filter body and the strippers, which is associated with accelerated wear.